Supported nickel catalysts are widely used in reduction reaction such as reforming reaction, hydrogenation and methanation for their high activity of nickel metal, and thus are industrially very important. In particular, supported nickel catalysts are used for steam reforming of natural gas, oil and naphtha, and thus for producing synthesis gas which is major starting material of C1-chemistry in chemical industry. These catalysts are also used in the production of synthesis gas which is raw material of methanol, ammonia and oxygen-containing compounds.
Examples of the processes for preparing supported nickel catalysts generally include co-precipitation, impregnation, ion exchange, precipitation-deposition, sol-gel, and aerogel methods. The propertiess of the catalysts vary depending on the method of preparation and treatment of the nickel catalysts.
German Patent Laid-Open Publication No.2,255,909 disclosed that Ni.sub.6 Al.sub.2 (OH).sub.16 CO.sub.3 4H.sub.2 O, a precursor of catalyst, was prepared by co-precipitation method, and then Ni-Al type catalyst was prepared by calcining the precursor and the catalyst was used for steam reforming reaction of naphtha. Another German Patent Laid-Open Publication No.2,024,282 disclosed that supported nickel catalyst which was steam reforming catalyst of methane was prepared by a co-precipitation method comprising adding Na.sub.2 CO.sub.3 to an aqueous solution containing 15.3% of Ni(NO.sub.3).sub.2 6H.sub.2 O and 7.6% of Al (NO.sub.3).sub.2 9H.sub.2 O.
Japanese Patent Laid-Open Publication No.57-156,303 suggested a method of loading a nickel metal component by an impregnating method on natural zeolite. In the specification, natural zeolite was added to a 1 molar of aqueous solution of Ni(NO.sub.3).sub.2, impregnated at 100.degree. C. for one hour and then calcined at 400.degree. C. for one hour. The prepared catalyst has a higher activity than that of a general nickel catalyst supported on alumina when used in the steam reforming reaction of natural gas.
Generally, supported nickel catalysts are mostly prepared by wet methods. However, these wet methods have problems that they require a drying step and acidic or basic waste water may be formed depending on preparing method. Therefore, these methods are difficult to apply the process industrially.
The present inventors have carried out extensive studies in order to solve the problems of the known wet methods and to find a process for preparing a supported nickel catalyst for reforming hydrocarbons with high activity without having a drying step and waste water problem. As a result, the present inventors have now found that by mixing a nickel salt and, if necessary, an alkali metal salt and/or alkaline earth metal salt with a silicon and/or aluminum-containing a support such as zeolite, silica and alumina, decomposing metal salts while melting all the salts and calcining the decomposed metals at 300.degree. C. to 1200.degree. C., supported nickel catalysts can be produced. The present invention has been attained on the basis of this finding.